C# 我在等你允许的var=总体.FindAll（x=>IsPermitted（x）） class Person { prop string compositeKey { get; set; } } class Exclusions { pro

我在等你<代码>允许的var=总体.FindAll（x=>IsPermitted（x））

class Person
{
    prop string compositeKey { get; set; }
}

class Exclusions
{
    prop string compositeKey { get; set; }
}

List<Person> people = GetFromDB;

List<Exclusions> exclusions = GetFromOtherDB;

List<Person> filteredResults = People - exclustions using the composite key as a comparer

public static bool In<T>(this T objToCheck, params T[] values)
{
    if (values == null || values.Length == 0) 
    {
        return false; //early out
    }
    else
    {
        foreach (T t in values)
        {
            if (t.Equals(objToCheck))
                return true;   //RETURN found!
        }

        return false; //nothing found
    }
}

List<Person> filteredResults = 
    people.FindAll(p => return !exclusions.Contains(p));

var difference = people.Except(exclusions);

var resultingList = 
    listOfOriginalItems.Except(listOfItemsToLeaveOut, equalityComparer)

var exclusionKeys = 
        exclusions.Select(x => x.compositeKey);
var resultingPersons = 
        persons.Where(x => !exclusionKeys.Contains(x.compositeKey));

static class Program
{
    public class Person
    {
        public string Key { get; set; }
        public Person(string key)
        {
           Key = key;
        }
    }
    public class NotPerson
    {
        public string Key { get; set; }
        public NotPerson(string key)
        {
           Key = key;
        }
    }
    static void Main()
    {

       List<Person> persons = new List<Person>()
       { 
           new Person ("1"),
           new Person ("2"),
           new Person ("3"),
           new Person ("4")
       };

       List<NotPerson> notpersons = new List<NotPerson>()
       { 
           new NotPerson ("3"),
           new NotPerson ("4")
       };

       var filteredResults = from n in persons
                             where !notpersons.Any(y => n.Key == y.Key)
                             select n;

       foreach (var item in filteredResults)
       {
          Console.WriteLine(item.Key);
       }
    }
 }

List<Person> filteredResults =from p in people
        join e in exclusions on p.compositeKey equals e.compositeKey into temp
        from t in temp.DefaultIfEmpty()
        where t.compositeKey == null
        select p

  var results = from p in People 
                where !(from e in exclusions 
                        select e.CompositeKey).Contains(p.CompositeKey) 
                select p;

            var result = Data.Where(x =>
            {
            bool condition = true;
            double accord = (double)x[Table.Columns.IndexOf(FiltercomboBox.Text)];
            return condition && accord >= double.Parse(FilterLowertextBox.Text) && accord <= double.Parse(FilterUppertextBox.Text); 
        });

var thisList = new List<string>{ "a", "b", "c" };
var otherList = new List<string> {"a", "b"};

var theOnesThatDontMatch = thisList
        .Where(item=> otherList.All(otherItem=> item != otherItem))
        .ToList();

var theOnesThatDoMatch = thisList
        .Where(item=> otherList.Any(otherItem=> item == otherItem))
        .ToList();

Console.WriteLine("don't match: {0}", string.Join(",", theOnesThatDontMatch));
Console.WriteLine("do match: {0}", string.Join(",", theOnesThatDoMatch));

//Output:
//don't match: c
//do match: a,b